Furnace emits a burning smell when running

Safety first: If you smell a strong burning plastic or electrical smell, turn off power immediately and do not operate the furnace until inspected.

• New season dust burn-off: A mild burning dust smell at first startup of the season is common and should dissipate after a few cycles. Ensure good ventilation.
• Inspect blower motor: Remove the blower door and check for signs of overheating (discolored paint, burnt smell near motor). If the motor is extremely hot to the touch (power off), it may be failing.
• Check wiring: Look for discolored or melted insulation on wires at the control board, blower, and gas valve. Tighten any loose connections.
• Clean interior: With power off, gently vacuum dust from accessible surfaces around the burners and heat exchanger (do not disturb sealed combustion areas).
• When to call a pro: Persistent burning smells or any sign of melted components require professional diagnosis.